This disclosure relates to liquid crystal displays (LCDs), in general, and in particular, to array substrates for LCD panels that improve the image quality of display panels incorporating them.
LCDs typically include an LCD panel that displays an image using the optical characteristics of a liquid crystal material, and a backlight assembly disposed behind the panel for projecting light though the panel.
The LCD panel typically includes an array substrate, a color filter substrate facing the array substrate, and a layer of the liquid crystal material interposed between the two substrates.
The array substrate includes gate and data lines that are disposed substantially perpendicular to each other to define a plurality of rectangular unit pixels, along with thin film transistors that are electrically connected to the gate and data lines, pixel electrodes that are formed in the unit pixels and electrically connected to the thin film transistors, and storage lines that overlap the pixel electrodes. The storage lines are arranged to overlap the pixel electrodes so as to form storage capacitors that maintain the voltage applied to each pixel electrode during one image frame.
The elements of the array substrate are typically formed through a photolithography process. For example, the pixel electrodes may be formed through an entire-surface deposition, or by an exposure-by-mask and an etching process. Recently, as the size of array substrates has become large in comparison with that of the masks used to produce them, the exposure-by-mask process must be performed repetitively in order to expose a single substrate. That is, the mask must be moved by a predetermined distance between each of the multiple exposures of the substrate.
However, when the pixel electrodes are formed through such a multiple exposure process, the pixel electrodes may be slightly misaligned with respect to the gate lines, the data lines and the storage lines. When the pixel electrodes are misaligned with respect to the storage lines, the storage capacitors that are formed between the pixel electrodes and the storage lines can vary spatially, and as a result, generate varying kickback voltages that cause flicker defects that deteriorate the image quality of the display.